Impact of elevated CO2 on two successive generations of CO2 responsive maize genotype

Abstract

A CO₂-responsive maize (Zea mays L.) genotype, Harsha, was selected to assess its response to elevated CO₂ in successive generation. The selfed seeds harvested from elevated CO₂ (eCO₂) raised maize plants were sown in open-top chambers (OTCs) to raise second generation (H-II) plants along with fresh seeds as first generation (H-I) under both ambient (400 ppm) and elevated (550 ppm) CO₂ (eCO₂) conditions. It was observed that second-generation (H-II) plants also showed improved performance under eCO₂ for morphological and physiological parameters. It is pertinent to mention that the H-II plants were more vigorous even under ambient CO₂ (aCO₂) condition as compared to H-I plants. The vigor of H-II plants was higher for majority of the morphological and biomass parameters under both aCO₂ and eCO₂. In H-II, the increased photosynthetic rate (Anet) was 6% and decrease in transpiration rate (Tr) was 49%, which resulted in significant increase (110%) in water use efficiency. This reveals that the elevated CO₂ improved the physiological performance of the maize plant over the generations. These results clearly elucidate that a C₄ crop like maize can respond to elevated CO₂ and higher response in subsequent generations may favor the crop resilience under changed climatic conditions